# Questions tagged [code-review]

This tag is intended for the review and improvement of style for already functioning code. It not meant to change the objective of the code.

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1 vote
48 views

### Why this code does not show three legend lines?

My code shows empty legend lines. What should I do to show the graph with three legend lines? ...
189 views

### Fixing a code which covers $[-k,k]\times[-k,k]$ for a given $k\in\mathbb{N}$, with smaller rectangles of equal area?

Motivation: From this post we, initially, wanted to cover a rectangle using smaller, non-overlapping rectangles with the same area: the difference between the total area of the smaller rectangles and ...
165 views

### Improve performance of Linear Optimization

EDIT I am reframing the question here by pulling out the relevant part about linear optimization, you can find the original question and the entire code down below. I am trying to increase the ...
385 views

### A simpler or more concise way to divide the boundary of a polygon into equal arc lengths?

I am really looking just for the least amount of code needed to do this but it is still readable. Here is the same polygon but the border is respectively split up into 10, 20, and 30 points along the ...
1 vote
162 views

### How to show the limit of two functions in a code approach zero?

I don't know how to shorten the program, the entire code is required to understand everything: ...
1 vote
61 views

### How to join two disconnected curves with listplot

Actually I want to join the blue and the red curve with another curve (definitely not a straight line, but some smooth curve) to show the transition from blue to red. How can I do this? Please help. ...
51 views

### Plotting diagram of complex equation [closed]

I have this equation: q1[t_] := -I*γ*Sin[θ] + ((γ*Cos[θ])/n^2)*(I*ξ[t]*y+z*α[t]) and the main code is the following with the definition of each parameters: ...
80 views

### Why is StoppingTest in red? What other option to stop NDSolve?

The following stripped down code works, but I'm experiencing some strange warnings: from an old document made with Mathematica 7.0 (but used in version 13.2), I'm getting several warning messages ...
155 views

### how to balance a matrix by proportional adjustment of rows and columns

Given a matrix: ClearAll[mat, refR, refC]; mat = { {21.2, 29, 19.9}, {9, 48.8, 22.4}, {49.8, 62.2, 7.8} }; I want to adjust the elements of ...
51 views

### Part specification error

I am doing a solved exercise shared here. However, while running the code, I encountered an error on page-8, under the Dynamics section. with error : I think this error is due to the absence of ...
1 vote
119 views

### Number operator

Suppose CR is my creation operator and AR is my annihilation operator. I have to show that ...
64 views

### Mathematical Equations Puzzle: Perfect Sixes

pI have given the following problem to my students Write some code that solves the perfect sixes problem for all numbers it works for! The perfect sixes problem asks you to solve some equations: \...
1 vote
95 views

### How can I roll up a line to get a circle? [closed]

I am trying to transfer n1=4 points that I have on a line, on a circle. suppose: ...
1 vote
96 views

### Matlab to Mathematica code to solve system of ODEs [closed]

I have the following system of second order non-homogeneous DEs: \begin{align} 0 &= 2 x_t - J_{\pi_t}(x_t) \frac{\epsilon - 1}{\theta} (1 + \varphi) + \frac{\partial J_{x_t}(x_t)}{\partial x_t} \...
32 views

### Discretizing Geographics

I am in need of boundary regions for cities. A previous question shows that it is possible to discretize CountryData: ...
52 views

### How to solve Equation for different variable in Mathematica?

I want to solve the given equation for $(n=m=3)$ and I want the output variable $q_{1,1}, q_{1,2}, q_{2,1}, q_{2,2}$ Given Equation Given Equation-2 The output should be required Output Here is my ...
89 views

### Create a set of vectors from given pairwise dot product

Assume I am given a list of all the pairwise dot products of an unknown set of $n$ vectors. How can I efficiently generate such a set (or all possible sets) with the extra constraint that all vectors ...
1 vote
101 views

591 views

### Mathematica for Theoretical Physics by Gerd Baumann : Henonmap

I was following a solved problem from the book mentioned below on the Henon map. However, even after correcting that I still get an error on execution. I am unable to find the exact cause. ...
1 vote
142 views

### Again with filling in a plot

I really don't understand how filling works, and here I am with a new question about. I need to colour the region in the first quadrant, created by the functions $x+2$ and $-3x+5$. Hence $x$ runs from ...
186 views

### Collapse (hide) code inside a function

I often use structures similar to the "func" below, however I would like to be able to "hide" the function definitions (similar to cell grouping using a group opener). I think an ...
94 views

### Speed up functions using variable types but not Compile

I am writing a large numerical code and I have set up many functions that take several arguments as input. In the functions I am using several built in Mathematica functions, such as Sum[], Part[], ...
112 views

### Unable to solve the given equation

I am trying to solve the given system in terms of $r$, for which I use the following code: ...
1 vote
163 views

### Plot of massless particles on unstable null circular geodesic : Finding an alternative for GraphicsMeshFindIntersections and reducing code length

My friend and I were trying to reproduce Figure 4(left) from this paper(page 7). We succeeded in reproducing the result after writing a lengthy and complicated code. Here I dissect the code in steps: ...
77 views

### Trouble with output of Reduce as a root object for a 3d Plot

I am trying to find the value of $r_0$ using $L^2=\frac{{r_0}^3 f'({r_0})}{2 f({r_0})-{r_0} f'({r_0})}$ and making a 3d plot with the help of the code given below: ...
186 views

### Converting specific positions of a List into Sublist

Suppose I have a List of numbers: num = Range I want to combine the second and the third element into a sublist to get the result as {1,{2,3},4,5}. I tried ...
1 vote
73 views

### Implementing a way of generating binary data for use in a logistic regression

Background I want to generate a set of test data to be used in a logisitic regression. As an example consider the scenario where a cannonball is fired at a wall. There are only two outcomes: the wall ...
1 vote
128 views

### How to increase efficiency of Mathematica code?

I have a code that runs as it is supposed to, but it takes around 8 hours to reach the solution with the step size necessary to find agreement between the analytical and computational solutions. As I ...
1 vote
126 views

### How can I improve this code?

The code below is working well, but it's very slow in the Manipulate box. I know that the Do and AppendTo parts aren't very ...
1 vote
79 views

### How to use an "otherwise" clause in Which

I want to classify a set of vectors according to the number and position of zeroes they contain. The components of the vectors are non-negative. I'm using ...
71 views

### How do we define the function near the end of my post?

Suppose I have two sets $F_{1,n}$ and $F_{2,n}$ written as: ...
412 views

### Is there a more elegant solution than f[a, b, Sequence@@#3,...]?

I am trying to construct a list of many possible combinations using Outer and Permutations. Something that looks like that: <...
1 vote
70 views

### How to rescale list to interval $(0,1)$ [closed]

Imagine I have an arbitrary list l = RandomReal[{-5, 10}, 10] Out[]= {4.17452, 1.75762, 4.16905, -3.63225, 8.34172, 5.39626, -4.2107, 3.50873, -1.52441, -3.7147} ...
91 views

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105 views

### Check certain expression using a while loop to run through all posibilities in a range

Well, I have written the following code (using the fast square root test found in this answer): ...
1 vote
48 views

### How to number each element of a list to form a table of points? [closed]

Suppose we have a list given below OurList={a,b,c,d,e} Is there a way to attribute a number to each element of OurList so that we could form a table of points? The ...
20 views

### Table of time-varing calculation slower to the point of kernel blowing up

There is a complicated function obtained by numerically solving a pde, let us call it $u(t,x,z)$. For this $u$, I want to calculate the global maximum of $u^2$ at a fixed position of $z$, and plot ...
130 views

### How to compile sum over the compiled expression?

Consider the following toy code: ...
1 vote
103 views

### How do we find the limit of my code?

Suppose we have the following: ...
1 vote
99 views

### How to fix Mathematica crashing in the following case?

I have a problem with Mathematica when trying to glue two tables together. The tables have the form ...
225 views

### Speeding up Fourier transform and eigenvector calculation

I have a matrix $M$ in Bloch basis (momentum space). Then I have to take Fourier transform of $M$ to go to real space. The size of this lattice in real space can be fixed to some value $N_{unit}$. ...
231 views

### Unbounded solution at boundaries with few combination of values in this BVP solution

I had asked a question here regarding solution to a BVP problem. bbgodfrey provided an excellent answer using the method of integrated least squares. However, for a few specific set of values of ...
1 vote
86 views

### Code review of my animation of Ellipsoid method

Feel free to suggest improvements (code-review) to my two functions (calculation and animation). They were made to visualize the workings of the Ellipsoid method in two dimensions. For example, see ...
1 vote
248 views

### How to fourier transform a numerical solution?

I numerically solved a wave equation and want to fourier transform the solution uwave1(t,x,z) at a particular instant of time t and position z. The code is as follows: ...
1 vote
89 views

### Shortest paths Knights Tour

I am trying to print the minimum steps needed to traverse a chessboard as a knight from one diagonal position to the other. I have the following code: Building the chessboard I started with creating ...
### Check if a fraction leads to an integer, choose $r$ and run trough $0\le a\le n$ and go to $r+1$
Well, I am trying to do the following: I have two functions $y(r,a)$ and $z(r,a)$ and I want to check of the division of both those functions leads to an integer. In order to do that I want to choose ...